Optical sub-assembly packaging techniques that incorporate optical lenses

ABSTRACT

Techniques for manufacturing an optical transmission device in a manner so that the photonic device is protected from damage that can be caused by exposure to the environment and physical handling are described. The invention involves placing a lens or a lens array over a photonic device, either with or without the use of a receptacle device, such that the photonic device is contained within a sealed cavity. The invention has three main embodiments in which the photonic device can be hermetically sealed, quasi-hermetically sealed, or non-hermetically sealed. The optical transmission device can be configured to serve as an optical receiver, detector, or a transceiver device.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is related to U.S. patent application Ser. No.09/568,094, entitled “DEVICE AND METHOD FOR PROVIDING A TRUESEMICONDUCTOR DIE TO EXTERNAL FIBER OPTIC CABLE CONNECTION,” filed onMay 9, 2000, which is now U.S. Pat. No. 6,364,542, to U.S. patentapplication Ser. No. 09/568,558, entitled “ARRAYABLE, SCALABLE ANDSTACKABLE MOLDED PACKAGE CONFIGURATION,” filed on May 9, 2000, to U.S.patent application Ser. No. 09/947,210, entitled “TECHNIQUES FOR JOININGAN OPTOELECTRONIC MODULE To A SEMICONDUCTOR PACKAGE,” filed on Aug. 3,2001, to U.S. patent application Ser. No. 10/006,443, entitled“TECHNIQUES FOR MAINTAINING PARALLELISM BETWEEN OPTICAL AND CHIP SUBASSEMBLIES,” filed on Nov. 19, 2001, to U.S. patent application Ser. No.09/922,358, entitled “MINIATURE SEMICONDUCTOR PACKAGE FOR OPTOELECTRONICDEVICES,” filed on Aug. 3, 2001, to U.S. patent application Ser. No.10/165,553, entitled “OPTICAL SUB-ASSEMBLY FOR OPTO-ELECTRONIC MODULES,”filed Jun. 5, 2002, to U.S. patent application Ser. No. 10/165,711,entitled “CERAMIC OPTICAL SUBASSEMBLY FOR OPTO-ELECTRONIC MODULES,”filed on Jun. 6, 2002, to U.S. patent application Ser. No. 09/922,357,entitled “OPTOELECTRONIC PACKAGE WITH DAM STRUCTURE TO PROVIDE FIBERSTANDOFF,” filed on Aug. 3, 2001, to U.S. patent application Ser. No.09/957,936, entitled “TECHNIQUE FOR PROTECTING PHOTONIC DEVICES INOPTOELECTRONIC PACKAGES WITH CLEAR OVERMOLDING,” filed on Sep. 21, 2001,to U.S. patent application Ser. No. 09/922,946, entitled “OPTOELECTRONICPACKAGE WITH CONTROLLED FIBER STANDOFF,” filed on Aug. 3, 2001, thecontent of each of which are hereby incorporated by reference.

FIELD OF THE INVENTION

[0002] The present invention relates generally to optical transmissiontechnologies, and more specifically to packaging techniques that protectphotonic devices from damage.

BACKGROUND OF THE INVENTION

[0003] Optical signal transmission techniques provide the ability totransmit broad bandwidths of data across large distances. For instance,in comparison to electrical signal transmissions over copper wires,light is attenuated less in fiber than electrons traveling throughcopper. Therefore multiple data streams within a single opticaltransmission medium can be transmitted at one time. Also, the lightsignals travel large distances before they attenuate to a point in whichregeneration of the light signals is required.

[0004] Optoelectronic devices, which are a combination of optical andelectrical components, are used to build optical networks. The opticalcomponents generate, receive, and transmit light signals while theelectrical components store and process the signals. Such opticalcomponents include devices such as light emitting and detecting devices,generally referred to as photonic devices, and optical fibers. Exemplaryelectrical components are semiconductor integrated circuit devices.Typically, photonic devices are electrically connected to semiconductordevices and the ends of optical fibers are positioned proximate to theactive areas of the photonic devices. In this way, the photonic devicesemit and detect light signals to and from the optical fibers and thesemiconductor devices drive the photonic devices and receive signalsfrom the photonic devices. Examples of such optoelectronic devices aredescribed in U.S. Pat. No. 6,364,542 issued to Deane et al. and in U.S.patent application Ser. No. 10/165,553, entitled “OPTICAL SUB-ASSEMBLYFOR OPTO-ELECTRONIC MODULES,” both of which are incorporated byreference.

[0005] Although various techniques have been developed to effectivelyconnect the optoelectronic components, improved techniques are stilldesirable in order to increase the transmission efficiency ofoptoelectronic devices and overall reliability. For instance, theoptical coupling efficiency between photonic devices and optical fiberscommonly requires improvement. In one specific aspect, light emittingdevices tend to be biased at high voltage levels, thereby emitting lightsignals that have high intensity levels. These high intensity levelscause the light signals to enter the optical fibers with relatively lowefficiency. Also, the durability of optoelectronic devices are commonlylimited by the photonic devices, which tend to be delicate devices thatare adversely affected by elements such as dust, moisture, printedcircuit board mounting flux residues, cleaning residues, and harshphysical handling.

[0006] In view of the foregoing, optoelectronic manufacturing techniquesto produce more efficient and reliable devices would be desirable.

BRIEF SUMMARY OF THE INVENTION

[0007] The present invention is directed to techniques for manufacturingan optical transmission device in a manner so that the photonic deviceis protected from damage that can be caused by exposure to theenvironment and physical handling. Such damage can be caused by moistureabsorption, dust collection, board mounting flux residues, cleaningresidues, wire bonding operations, optical fiber mounting operations,etc. The invention involves placing a lens or a lens array over aphotonic device, either with or without the use of a receptacle device,such that the photonic device is contained within a sealed cavity. Theinvention has three main embodiments—a hermetically sealed photonicdevice, a quasi-hermetically sealed photonic device, and anon-hermetically sealed photonic device. The optical transmission devicecan be configured to serve as an optical receiver, detector, or atransceiver device.

[0008] One aspect of the invention pertains to an optical transmissiondevice in which a photonic device is hermetically sealed within aprotective cavity. This optical transmission device includes animpermeable support block having a supporting surface and a mountingsurface, electrical traces, at least one photonic device attached to arespective one of the cathode pads and connected to at least one of theanode pads, a metal boundary line formed on the support surface thatencircles the photonic device, and a glass lens set on top of the metalboundary line such that it is attached to the support surface of thesupport block.

[0009] Another aspect of the invention pertains to an opticaltransmission device in which a photonic device is sealed within anquasi-hermetic cavity. This optical transmission device includes animpermeable support block having a supporting surface and a mountingsurface, two raised and parallel rails formed on the supporting surfaceand being integrally formed with the support block, the two parallelrails forming a groove that runs between each of the rails, an elastico-ring that is set within the groove, electrical traces, a firstphotonic device, a receptacle that is attached to the supportingsurface, the receptacle having a protruding rim that conforms to theoutline of the parallel rails and which is set within the groove, thereceptacle also having a first receptacle opening, and a first glasslens attached within the first receptacle opening.

[0010] Yet another aspect of the invention pertains to an opticaltransmission device in which a photonic device is sealed within anon-hermetic cavity. This optical transmission device includes a supportblock having a supporting surface and a mounting surface, electricaltraces, a first photonic device, and a receptacle that is attached tothe supporting surface, the receptacle securing a first glass lens suchthat is it positioned above the first photonic device, the receptaclealso having a protruding rim that is in contact with the supportingsurface, the receptacle having a receptacle cavity that fits over thephotonic device whereby the photonic device is sealed between thesupporting surface and the receptacle.

[0011] These and other features and advantages of the present inventionwill be presented in more detail in the following specification of theinvention and the accompanying figures, which illustrate by way ofexample the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The invention, together with further advantages thereof, may bestbe understood by reference to the following description taken inconjunction with the accompanying drawings in which:

[0013]FIG. 1 illustrates one embodiment of an unassembled optoelectronicsystem designed to protect photonic device 106 within a hermeticallysealed environment.

[0014]FIG. 2 illustrates a side, cross-sectional view of optoelectronicsystem of FIG. 1.

[0015]FIG. 3 illustrates an alternative embodiment of an optoelectronicsystem wherein a photonic device is hermetically sealed.

[0016]FIG. 4 illustrates a cross-sectional view of an optoelectronicsystem according to another alternative embodiment of the presentinvention.

[0017]FIG. 5 illustrates a perspective view of a support block and achip subassembly, which form an alternative embodiment of anoptoelectronic system in which a photonic device is to be enclosedwithin a quasi-hermetic enclosure.

[0018]FIG. 6 illustrates a side cross-sectional view of optoelectronicsystem in which a support block and a receptacle are shown in anunassembled arrangement.

[0019]FIG. 7 illustrates a perspective view of an optoelectronic systemthat encloses a photonic device within a non-hermetic enclosure,according to one embodiment of the invention.

[0020]FIG. 8 illustrates a side plan, cross-sectional view of theoptoelectronic system shown in FIG. 7.

[0021]FIG. 9 illustrates a top plan, cross-sectional view of anoptoelectronic system that encloses photonic devices within anon-hermetic enclosure, according to an alternative embodiment of theinvention.

[0022]FIG. 10 illustrates an alternative embodiment of a support blockthat is designed to seal a photonic device within a quasi-hermeticenvironment.

DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention will now be described in detail withreference to a few preferred embodiments thereof as illustrated in theaccompanying drawings. In the following description, numerous specificdetails are set forth in order to provide a thorough understanding ofthe present invention. It will be apparent, however, to one skilled inthe art, that the present invention may be practiced without some or allof these specific details. In other instances, well known operationshave not been described in detail so not to unnecessarily obscure thepresent invention.

[0024] The present invention pertains to techniques for manufacturing anoptical transmission device in a manner so that the photonic device isprotected from damage resulting from exposure to the environment andphysical handling. Such damage can be caused by moisture absorption,dust collection, board mounting flux residues, cleaning residues, wirebonding operations, optical fiber mounting operations, etc. Theinvention involves placing a lens or a lens array over a photonicdevice, either with or without the use of a receptacle device, such thatthe photonic device is contained within a sealed cavity. The inventionhas three main embodiments—a hermetically sealed photonic device, aquasi-hermetically sealed photonic device, and a non-hermetically sealedphotonic device. The optical transmission device can be configured toserve as an optical receiver, detector, or a transceiver device.

[0025]FIG. 1 illustrates one embodiment of an unassembled optoelectronicsystem 100 designed to protect photonic device 106 within a hermeticallysealed environment. Upon assembly, optoelectronic system 100 can be usedto convert optical signals to electronic signals and vice-versa. System100 can be used to build an optical network. Optoelectronic system 100is made up of the following components. First there is the opticalsubassembly 102, which includes a support block 104 and a photonicdevice 106. Photonic device 106 is attached to a front surface 108 ofsupport block 104. Secondly, there is the semiconductor device package(or the chip subassembly) 110, which is a semiconductor integratedcircuit (IC) device that is packaged within a protective body. The ICdevice within package 110 is electrically connected to photonic device106 in order to send and receive signals from photonic device 106. TheIC device and photonic device 106 can be electrically connected byelectrical traces that run along or through the body of support block104.

[0026] Thirdly there is a lens 112 that, when assembled, is attached tosupport surface 108 of support block 104 in order to protect photonicdevice 106. Lens 112 is shaped like a cap or an open-ended box. Itsopen-end is to be placed onto the surface of support block 104 so thatlens 112 covers photonic device 106 and seals photonic device 106 in ahermetically sealed environment. Then there is a receptacle 114, whichis to be attached to lens 112. Then a ferrule 116, which holds opticalfibers 118 in place, is attached to receptacle 114. After being fullyassembled, optical fibers 118 are in optical communication with photonicdevice 106 and the optical signals that pass through fibers 118 gettranslated into electrical signals within chip subassembly 110, andvice-versa.

[0027]FIG. 2 illustrates a side, cross-sectional view of optoelectronicsystem 100 of FIG. 1. FIG. 2 provides an additional view ofoptoelectronic system 100 to facilitate a more thorough understanding ofthe present invention.

[0028] The main function of support block 104 is to support photonicdevice 106 so that optical fibers 118 can conveniently be set in opticalcommunication with photonic device 106. To perform this function,support block 104 is formed to have front surface (or supportingsurface) 108 and a bottom surface that is attached to chip subassembly110. In one embodiment, support block 106 is made of an impermeablematerial such as a ceramic. An impermeable material prevents moisture topass through support block 104. By making support block 104 out of animpermeable material, it is possible to hermetically seal photonicdevice 106 within lens 112. In alternative embodiments, support block104 can be formed of permeable materials if it is not important toprotect photonic device 106 from moisture absorption. For instance,support block 104 could be formed of plastic or FR4.

[0029] In one embodiment, lens 112 is made of glass because theimpermeable properties of glass is used to ensure a hermetic seal ofphotonic device 106 between support surface 108 and lens 112. Lens 112can be formed of molded high-index glass material. Lens 112 can beeither a single lenslet or an array of lenslets.

[0030] In alternative embodiments in which a hermetic sealing ofphotonic device 106 is less important, lens 112 can be made of opticalgrade plastics. This is possible when a solder reflow is not requiredafter the lens 112 is attached to the ceramic support block 102 or thesolder reflow can be carried out at relatively low temperature (lowerthan 220 degrees Celsius).

[0031] The cavity within lens 112 is referred to as a lens cavity 126.Lens 112 can be placed over photonic device 106 so that photonic device106 fits within lens cavity 126. Rim 124 of lens 112 is rectangularshaped, however, it can have a variety of outline shapes. For example,lens 112 could have a rim 124 that has an oval outline shape instead ofa rectangular shape.

[0032] In order to create a hermetic seal between support surface 108and lens 112, a line of metal material 120 is formed around theperimeter of photonic device 106. Metal line 120 can be referred to as ametal boundary line 120. A matching line of metal material 122 is formedaround a rim 124 of lens 112. Lens 112 is then attached to supportsurface 108 by placing the lines of metal 120 and 122 together andsolder reflowing them together. Metal boundary line 120 acts as ahermetic sealing joint between lens 112 and support surface 108 suchthat gas and moisture cannot seep between lens 112 and support surface108. Alternative methods of using a metal connecting joint betweensupport surface 108 and lens 122 can also be utilized.

[0033] In order to create a hermetic seal around photonic device 106,the materials used to surround photonic device are impermeablematerials. As described above, each of the lens 112, support block 104,and boundary lines 120 are formed of ceramics, metal, or glass.Materials that are not used include those that allow for seepage ofmoisture, such as polymers and epoxy adhesives. For instance, polymersand epoxy tend to absorb moisture or outgas and therefore introducemoisture or gas into an environment.

[0034] Interconnecting wires 128 connect anode pads on the surface ofphotonic device 106 to anode contact pads 130 on supporting surface 108.Anode contact pads 130 are within the limits of metal boundary line 120so that they will also be contained within a hermetically sealedenvironment when lens 112 is attached to support surface 108.Interconnecting wires 128 are typically wirebonded onto photonic device106 and anode contact pad 130 in such a way that the wires 128 extendoutwards from photonic device and then bend back towards anode contactpads 130. Lens cavity 126 should have a stand-off height, H_(SO), thatis large enough to allow lens 112 to be placed over photonic device 106without having interconnecting wires 128 touch the inner surface of lens112. Standoff height, H_(SO), is the distance between the inside surfaceof lens 112 and support surface 108 after lens 112 is attached.

[0035] By hermetically sealing photonic device 106 between supportsurface 108 and lens 112, photonic device 106 is protected from theelements, such as dust and moisture. Such elements can adversely affectthe operation and reliability of photonic devices. The photonic die, orarrays, will be completely sealed from the outside and no moisture willbe able to diffuse into the photonic cavity. The residual moisturewithin the cavity will depend on the process used during sealing and onthe product reliability requirements. Most hermetic packages currentlyfollow Mil Specs of less than 5000 ppm of moisture content. Suchprotection provides full protection of the photonics during componenthandling, board assembly, and field operations.

[0036] Lens 112 also serves to protect photonic device 106 from physicaldamage that can be sustained during handling and use.

[0037] Lens 112 can also increase the coupling efficiency betweenoptical fibers 118 and photonic device 106. With respect to a lighttransmitting photonic devices, lens 112 can attenuate the light emittedfrom photonic device so that the emitted light has a smaller intensityupon entering an optical fiber. This is useful since light transmittingphotonic devices are typically biased at higher than needed voltagelevels in order to operate at sufficiently high data rates. In turn,this causes the emitted light to have a higher intensity level than itis needed, which causes a safety issue. Therefore, by attenuating theemitted light with lens 112, a safe operation can be achieved whilerequired data rate can be met. On the other hand, with respect to lightreceiving photonic devices, lens 112 can magnify or focus light receivedfrom optical fibers so that a higher intensity light signal can bedirected into photonic device 106. This can also increase the couplingefficiency between a photonic device and an optical fiber.

[0038] When optoelectronic system 100 supports a light detectingphotonic device, it operates as a receiving device. When optoelectronicsystem 100 supports a light transmitting photonic device, it operates asa transmitter. In some embodiments, optoelectronic system 100 cansupport both a light detector and a light receiver, thereby makingsystem 100 a transceiver. Optoelectronic system 100 can support one ormore photonic devices to create a multi-channel receiver, transmitter,or transceiver. In these embodiments, a single lens 112 can be placedover all of the photonic devices or one lens can be placed over eachphotonic device. When multiple lenses are used, multiple metal boundarylines 120 should also be formed on support surface 108 and correspondingmetal lines 122 should also be formed on the rims of each of lenses 112in order to form a hermetic seal within each of the lens cavities 126.When a light transmitting and a light emitting photonic device isattached to a support surface 108, two types of lenses can be used. Oneof the lenses can be a light attenuating lens that is placed over thelight emitting photonic device. Another type of lens can be a lightmagnifying lens that is placed over the light receiving photonic device.

[0039] Chip subassembly 110, as seen in FIG. 2, includes a semiconductordie 200 that is mounted on top of a die attach pad 202 and encapsulatedwithin a protective molding material 204. Up-linking contacts 206 areformed on the top surface of die 200 in order to form an electricalpathway to connect die 200 with photonic device 106. Interconnectingwires 208 connect die 200 to chip contact pads 209, which form thecontact surfaces through which optoelectronic system 100 can beconnected to a printed circuit board or another electronic system. Chipsubassembly 110 in FIG. 2 is referred to as a leadless leadframesemiconductor chip package. However, alternative embodiments of chipsubassembly 110 that have contact surfaces for both making contact withsupport block 104 and an external system can also be used. For instance,standard dual in-line packages, ball grid array packages, and quad-flatpackages can also be used.

[0040] Chip subassembly 110 can have various types of contacts forconnection to an electrical system such as a printed circuit board. Thecontacts can be flush with the side surfaces or extend past theperipheral side surfaces. In this way, the CSA can be hotbar reflowed,surface mount reflowed, pluggable. Also the CSA can have a configurationto allow for mounting onto an edge or anywhere on a printed circuitboard.

[0041] Up-linking contacts 206 connected to contact pads 210 on thebottom surface of support block 104. Electrically conductive adhesive orsolder 211 can be used to secure this connection. Underfill material 212is used to fill in the gaps between support block 106 and chipsubassembly 110 in order to strengthen the connection between the twocomponents.

[0042] Receptacle 114 attaches to lens 112 and forms an attachment areafor ferrule 116. Ferrule 116 is a device that secures one or moreoptical fibers 118. As shown in FIG. 1, ferrule 116 secures a ribbon ofoptical fibers 118. Receptacle 114 has a receptacle opening 115 thatallows light from optical fibers 118 to travel through lens 112 in orderto reach photonic device 106. Receptacle 114 is attached to lens 112 byinserting lens 112 into the receptacle opening 115. Then adhesivematerial 132 is used to secure the connection. Adhesive material can beglue since a hermetic seal between receptacle 114 and lens 112 is notcritical. In the various embodiments of the invention where a lens isattached to a receptacle, the lens can be attached to the receptacle byeither placing the lens within an opening of the receptacle or byattaching the rim of the opening to a front surface of the lens, as willbe described in FIG. 3.

[0043] Receptacle 114 has alignment pins 117 that guide ferrule 116 intothe correct alignment with receptacle 114. Correct alignment betweenferule 116 and receptacle 117 ensures that optical fibers 118 willcorrectly align with photonic device 106. Receptacle 114 can be made tohave various sizes and shapes suitable for attaching a ferrule 116 to alens 112.

[0044] Manufacturing optoelectronic system 100 involves at least twoseparate soldering operations. First, solder is used to attach lensarray 112 onto support surface 108 of support block 104. Secondly,solder is used to attach optical subassembly 102 onto chip subassembly110. Proper selection of high-temperature solders is required to followa manufacturing thermal hierarchy. Exemplary high-temperature soldershave high lead content (e.g., 10Sn90Pb, or 5Sn95Pb, or 3Sn97Pb) withmelting points greater than 300° C. In other words, manufacturingprocess steps should expose the optoelectronic system 100 to a hierarchyof decreasing temperature exposure so to not adversely affect theintegrity of interfaces and components assembled in earlier steps. Forinstance, since lens 112 is attached to support surface 108 beforeoptical subassembly 102 is attached to chip subassembly 110, the meltingpoint of the solder used between lens 112 and support surface 108 shouldbe higher than the solder used between optical subassembly 102 and chipsubassembly 110. High-temperature solder should be used for sealing lens112 to support surface 108. Eutectic solder (63Sn37Pb, meltingpoint=183° C.) can be used to connect optical subassembly 102 and chipsubassembly 110. By following this temperature hierarchy, the solderseal between lens 112 and support surface 108 can remain intact duringthe process of attaching optical subassembly 102 to chip subassembly110.

[0045] Epoxy can be used to attach components outside of the lens cavity126. For instance, epoxy can be used to attach the receptacle to thelens and the ferrule to the receptacle.

[0046] Support block 104 is an low temperature co-fired ceramics (LTCC)module that is formed of multiple laminated layers 214 of ceramicmaterial. Metal traces 216 are formed between some of the adjacentceramic layers 214 and conductive vias 218 that pass through thethickness of the layers 214 connect the metal traces 216. The network ofmetal traces 216 and conductive vias 218 connect the contact pads 210with the anode contact pads 130 and a cathode pad 134 on the supportsurface 108. This network of electrical traces 216 and conductive vias218 is convenient for maintaining a hermetic seal around photonic device106 since the traces 216 and vias 218 are not exposed to the environmentand therefore do not provide a pathway for moisture to seep into thelens cavity 126.

[0047]FIG. 3 illustrates an alternative embodiment of an optoelectronicsystem 300 wherein photonic device 308 is hermetically sealed. Onedifference between system 300 and system 100 of FIGS. 1 and 2 is thatsupport surface 302 of support block 304 has a recessed surface cavity306 and a photonic device 308 sits within surface cavity 306. A seconddifference is that lens 310 is substantially flat. Surface cavity 306 isrecessed to a depth such that when lens 310 is attached to supportsurface 302, interconnecting wires 312, which extend from the topsurface of photonic device 308, do not touch lens 310. The depth ofsurface cavity 306 depends upon the thickness of photonic device 308 andthe height of interconnecting wire 312. The depth of surface cavity 306should be set so that interconnecting wires 312 do not touch lens 310.In some embodiments, the surface cavity 306 can extend through multipleceramic layers. In some embodiments, lens 310 can have a cap shape asshown in FIGS. 1 and 2.

[0048] Anode contact pads 314 are formed on at a level that is higherthan the level upon which the photonic device 308 is set. This allowsshorter interconnecting wires 312 to connect photonic device 308 andanode contact pads 314. The height at which anode contact pads 314 canvary depending upon design requirements.

[0049] Another difference with optoelectronic system 300 is thatphotonic device 308 is wirebonded to anode contact pads 314 that arelocated above, as well as below, photonic device 308.

[0050] As with system 100 of FIGS. 1 and 2, optoelectronic system 300hermetically seals photonic device 308 between surface cavity 306 andlens 310. Impermeable materials are used to form optoelectroniccomponents immediately surrounding photonic device 308. For instance,support block 304 can be formed of ceramic, lens 310 is formed of glass,and metal boundary lines 316 and 318 are used to attach lens 310 tosupport surface 302 via solder reflow.

[0051] Optoelectronic system 300 can also be formed to have multiplesurface cavities 306 that each can contain a photonic device 308. Eachphotonic device 308 can either be an optical transmitter or receiver.Each surface cavity 306 is also covered with a respective lens 310. Eachlens 310 can also be specially manufactured to either magnify orintensify a light signal to increase optical coupling efficiency. Insome embodiments, a single lens can have a region that magnifies lightwhile another region attenuates light signals. Each lens 310 is attachedto support block 304 through metal boundary lines 316 to ensure thehermetic seal around surface cavity 306.

[0052]FIG. 4 illustrates a cross-sectional view of an optoelectronicsystem 400 according to another alternative embodiment of the presentinvention. In system 400, multiple electrical traces 402 run along thesupporting surface 404 and the bottom surface 406 of support block 408.Electrical traces 402 connect cathode pad 410 and anode contact pads 412to respective contact pads located on bottom surface 406 of supportblock 408 thereby facilitating the electrical connection betweenphotonic device 414 and chip subassembly 416. Electrical traces 402 areshown to be embedded within support surface 404 and bottom surface 406.However, electrical traces 402 can also be formed on top of thesesurfaces. In order to preserve the hermetic seal within which photonicdevice 414 is contained, a layer of glass 415 is formed over electricaltraces 402. In this way, the electrical traces will not create a channelunderneath lens 418 through which air or moisture can seep into lenscavity 420. This can happen if gaps between electrical traces 402 andthe surrounding structure of support surface 404 form. These gaps can beso large that metal boundary lines 422 and 424 cannot sufficiently fillin these gaps to ensure a hermetic seal. Therefore, glass layer 415 isformed over electrical traces 402 and the portion of support surface 404surrounding each of electrical traces 402. As shown in FIG. 4, glasslayer 415 also covers substantially all of support surface 404 andbottom surface 406 except for the areas where conductive contact padsare located. Specifically, no glass layer is formed on support surface404 where cathode pad 410 and anode contact pad 412 are formed, and noglass layer is formed on bottom surface 406 wherever contact pads formaking contact with chip subassembly 416 are formed. In an alternativeembodiment, glass layer 415 can be formed in a more limited area thatincludes only a region where the rim of lens 418 makes contact withsupport surface 404. This glass lens formation would encircle photonicdevice 414, cathode pad 410, and anode contact pads 412.

[0053] Glass layer 415 can be applied to support block 408 using varioustechniques such as sputtering. Again, support block 408 is formed of animpermeable material such as a ceramic.

[0054]FIG. 5 illustrates a perspective view of a support block 502 and achip subassembly 504, which form an alternative embodiment of anoptoelectronic system 500 of the present invention. FIG. 6 illustrates aside cross-sectional view of optoelectronic system 500 in which supportblock 502 and receptacle 508 are shown in an unassembled arrangement.Optoelectronic system 500 is designed to seal photonic device 506 withina quasi-hermetic cavity. The packaging of system 500 is formed bysetting receptacle 508 within a groove 510 that surrounds photonicdevice 506. Receptacle 508 has an opening that secures an optical lens524. Optical lens 524 can be secured to receptacle 508 with adhesivessuch as an epoxy. Receptacle 508 and lens 524 combination forms areceptacle cavity 526 which is placed over photonic device 506 andthereby creates a quasi-hermetic seal over photonic device 506.

[0055] A high temperature elastic o-ring 512, which is set within groove510, helps seal the enclosed area surrounding photonic device 506.O-ring 512 is loop of elastic material that conforms to the outlineshape of groove 510 that encircles photonic device 506. The enclosurearound photonic device is quasi-hermetic because o-ring is typicallymade out of heat resistant rubber, silicone, or other polymers, whichallows for the transmission of moisture. The polymers used to formo-ring 512 will, over time, allow some moisture to diffuse in (and out)of the enclosure to reach certain equilibrium. This equilibrium will begoverned by the operating conditions of the module (e.g., power on thephotonics, heat dissipated by the photonic device 506, and the externalenvironment).

[0056] Another reason why photonic device 506 is sealed within aquasi-hermetic enclosure is because common adhesives, such as epoxy, areused to secure lens 524 within receptacle 508. As mentioned above, mostof such adhesives tend to outgas and therefore introduce gases into theenclosure. Low outgassing polymer materials are now commerciallyavailable and the materials that cure without outgassing are beingdeveloped.

[0057] Groove 510 is created with the parallel set of rails 516 that runaround the perimeter of photonic device 506. Rails 516 are integrallyformed from the material of the supporting surface 518 of support block502. Receptacle 508 has a protruding receptacle rim 520 that is designedto fit into groove 510. O-ring 512 will correspondingly be compressedwhen rim 520 is set into groove 510. O-ring 512 serves to seal theenclosed area between receptacle 508 and support surface 518. Theheight, width, and separation of rails 516 can be adjusted dependingupon the size of the o-ring and the size of receptacle rim 520 that isto be inserted into groove 510.

[0058] Standoff stems 522 also extend from receptacle 508. Standoffstems 522 make contact with support surface 508 and maintain a certaindistance between receptacle 508 and support surface 518. Specifically,support stems 522 maintain a separation distance between conductiveinterconnecting wires 528 and lens 524. Interconnecting wires 528 tendto be fragile and are easily broken. Therefore, standoff stems 522 serveto protect interconnecting wires 528 and the connection of photonicdevice 506 to the electrical traces within support block 502. Standoffstems 522 can be multiple individual stems or a continuous rim thatextends around rim 520. The shape and size of standoff stems 522 canvary so long as stems 522 serve to maintain the required separationdistance between lens 524 and support surface 518.

[0059] Standoff stems 522 are located outside of the receptacle rim 520and therefore make contact with support surface 518 outside of thequasi-hermetically sealed receptacle cavity 526. Standoff stems areattached to support surface 518 using adhesive material 530. In analternative embodiment, standoff stems 522 are located within theboundary created by receptacle rim 520.

[0060] Receptacle 508 can be formed of various materials such asplastic. Support block 502 need not be formed of impermeable materialsince the system 500 is a quasi-hermetic packaging configuration.However, in some embodiments, support block 502 can be formed of aceramic material.

[0061] In an alternative embodiment, optoelectronic system 500 can bemanufactured so that more than one receptacle can be attached to supportsurface 518. In this embodiment, support surface 518 can have multiplesets of parallel rails 516 and associated grooves 510. In this case,support surface would likely support multiple photonic devices 506, eachbeing covered by a respective receptacle and lens combination.

[0062] In another embodiment, one receptacle has multiple openings witheach opening supporting an optical lens. Each optical lens is supportedover a photonic device and can be tailored to either intensify orattenuate light signals. In all embodiments of optoelectronic system500, either light emitting or receiving devices can be attached tosupport surface 518 to create an optical transmitter, receiver, ortransceiver.

[0063]FIG. 10 illustrates an alternative embodiment of a support block1000 that is designed to seal a photonic device 1002 within aquasi-hermetic environment. Support block 1000 is different in thatgroove 1004 is set into the surface of block 1000. Groove 1004 encirclesphotonic device 1002 such that it has a circular or ovular outline shapeon the supporting surface of support block 1000. Forming the insetgroove 1004 allows protruding rails, as shown in FIGS. 5 and 6, to beoptional. Actually, FIG. 10 does not utilize any protruding rails toform groove 1004. O-ring 1006 is set within groove 1004 and will besquashed when rim 1008 is inserted into groove 1004. The squashed o-ring1006 acts to seal the connection between groove 1004 and rim 1008. Inthe embodiment of FIG. 10, rim 1008 is taller than rim 520 of FIGS. 5and 6 since rim 1008 must extend into the inset groove 1004. Rim 1008will also be taller than support stems 1010 since support stems 1010make contact with the surface of support block 1000.

[0064]FIG. 7 illustrates a perspective view of an optoelectronic system700 that encloses a photonic device 702 within a non-hermetic enclosure,according to one embodiment of the invention. FIG. 8 illustrates a sideplan, cross-sectional view of optoelectronic system 700 shown in FIG. 7.Photonic device 702 is enclosed within a receptacle cavity 704 that iscreated with receptacle 706 and lens 708. Receptacle 706 has an openingthat secures lens 708 so that lens 708 will be secured over photonicdevice 702. Lens 708 is secured to receptacle 706 with adhesive material709, such as epoxy. Receptacle 708 also has a receptacle rim 710 thatencircles lens 708. Receptacle rim 710 defines part of receptacle cavity704 and is attached to support surface 712 of support block 714 withadhesive material 716. The use of adhesive material to attach lens 708to receptacle 706 and receptacle 706 to support surface 712 allows thepossibility of the adhesive materials to outgas into receptacle cavity704. Because of this, receptacle cavity 704 is not completelyhermetically sealed. In one embodiment, a low shrinkage, low moistureabsorption and low out-gassing epoxy material is used as the adhesiveagent.

[0065] Photonic device 702 is protected from physical damage sincereceptacle rim 710 is a solid rim that completely encircles lens 708.This configuration allows photonic device 702 to be completely sealedwithin receptacle 706 and lens 708. In an alternative embodiment,receptacle rim 710 can be composed of individual stems that do notenclose photonic device 702 within a completely enclosed receptaclecavity 704.

[0066]FIG. 9 illustrates a top plan, cross-sectional view of anoptoelectronic system 900 that encloses photonic devices 902 and 904within a non-hermetic enclosure, according to an alternative embodimentof the invention. System 900 includes a receptacle 906 that has twoopenings that each secure a respective optical lens 908 and 910. Lenses908 and 910 are secured within the openings with an adhesive agent suchas epoxy. Lenses 908 and 910 can be designed to either intensify orattenuate light signals depending upon the type of photonic device thatthey cover. Again, photonic devices 902 and 904 can both be opticaltransmitters, optical receivers, or one of each.

[0067] Receptacle 906 is attached to supporting surface 912 of supportblock 914 at points surrounding each of photonic devices 902 and 904.Receptacle 906 is attached to support surface 912 with receptacle rim916, which completely surrounds photonic devices 902 and 904. Receptaclebar 918 extends between photonic devices 902 and 904 provides foradditional attachment regions between receptacle 906 and support surface912. Receptacle bar 918 is a solid structure that completely separatesphotonic devices 902 and 904. Receptacle rim 916 and bar 918 completelyenclose photonic devices within respective enclosures and therebyprotect photonic devices 902 and 904 from structural damage. Receptaclerim 916 and receptacle bar 918 are attached to support surface 912 withadhesive material 920.

[0068] In alternative embodiments, receptacle rim 916 and bar 918 can besubstituted with multiple standoff stems that are separate from eachother.

[0069] While this invention has been described in terms of severalpreferred embodiments, there are alteration, permutations, andequivalents, which fall within the scope of this invention. It shouldalso be noted that there are many alternative ways of implementing themethods and apparatuses of the present invention. It is thereforeintended that the following appended claims be interpreted as includingall such alterations, permutations, and equivalents as fall within thetrue spirit and scope of the present invention.

We claim:
 1. An optical transmission device comprising: an impermeablesupport block having a supporting surface and a mounting surface, thesupporting face having at least one cathode pad and a plurality of anodepads, and the mounting face having a plurality of contact pads;electrical traces that connect the cathode pad and the anode pads withrespective contact pads; at least one photonic device attached to arespective one of the cathode pads and connected to at least one of theanode pads; a metal boundary line formed on the support surface thatencircles the photonic device; and a glass lens set on top of the metalboundary line such that it is attached to the support surface of thesupport block, the glass lens configured to hermetically seal thephotonic device between the support surface and the glass lens wherebythe photonic device is protected from environmental and structuraldamage.
 2. An optical transmission device recited in claim 1 wherein theglass lens further comprises: an outer rim having a shape that conformsto and is attached to the metal boundary line, and a lens cavity thatfits over the photonic device.
 3. An optical transmission device recitedin claim 2 further comprising: at least one interconnecting wire thatextends outwardly from a top surface of the photonic device and thenbends back to make contact with one of the anode pads, whereby theinterconnecting wire serves to connect the photonic device to the anodepad; and wherein the lens cavity has a stand-off depth that issufficiently large so that the interconnecting wire fits within the lenscavity without touching the glass lens.
 4. An optical transmissiondevice recited in claim 1 wherein the supporting surface furthercomprises: a surface cavity that contains the cathode pad, the anodepads, and the photonic device.
 5. An optical transmission device recitedin claim 4 wherein the glass lens is substantially a flat piece of glassand wherein the glass lens hermetically seals the photonic device withinthe surface cavity.
 6. An optical transmission device recited in claim 5further comprising: at least one interconnecting wire that extendsoutwardly from a top surface of the photonic device and then bends backto make contact with one of the anode pads, whereby the interconnectingwire servers to connect the photonic device to the anode pad; andwherein the surface cavity has a stand-off depth that is sufficientlylarge so that the interconnecting wire fits within the surface cavitywithout touching the glass lens.
 7. An optical transmission devicerecited in claim 1 wherein the support block is formed of ceramic.
 8. Anoptical transmission device recited in claim 7 wherein the support blockis formed of multiple laminated layers of ceramic material, and whereinthe electrical traces are formed by a plurality of conductive pathwaysthat are sandwiched between adjacent ceramic layers and conductive viasthat pass through the thickness of each of the ceramic layers in orderto connect the conductive pathways.
 9. An optical transmission devicerecited in claim 1 wherein the supporting surface and the mountingsurface form a corner of the support block, and wherein the electricaltraces extend from the cathode and anode pads along the supportingsurface, wrap around the corner, and extend along the mounting surfaceuntil they make contact with the contact pads.
 10. An opticaltransmission device recited in claim 9 wherein a layer of glass isformed over at least a portion of the support surface and the mountingsurface, the glass layer covering at least the electrical traces suchthat they are hermetically sealed between the support block and theglass layer.
 11. An optical transmission device recited in claim 10wherein the metal boundary line is formed on top of the glass layerwhereby the glass lens is connected to the support block through boththe metal boundary line and the glass layer.
 12. An optical transmissiondevice recited in claim 10 wherein the glass layer has openings on themounting surface through which the contact pads are exposed.
 13. Anoptical transmission device recited in claim 1 further comprising: apackaged semiconductor device package that includes a semiconductor diethat is packaged within a protective molding material, a first set ofelectrical contact surfaces that are attached to the contact pads on themounting surface of the support block, and a second set of contactsurfaces capable of being connected to an external system.
 14. Anoptical transmission device recited in claim 1 further comprising: areceptacle that is attached to the glass lens, the receptacle having anopening through which the glass lens is exposed such that an opticalpathway from the photonic device, through the glass lens and through theopening in the receptacle is provided.
 15. An optical transmissiondevice recited in claim 1 further comprising: a second photonic deviceattached to a respective one of the cathode pads.
 16. An opticaltransmission device recited in claim 15 wherein each of the photonicdevices is an optical receiver or transmitter whereby the opticaltransmission device can serve as a detector, transmitter, or atransceiver.
 17. An optical transmission device comprising: animpermeable support block having a supporting surface and a mountingsurface, the mounting surface having a plurality of contact pads, andthe supporting surface having at least one cathode pad and a pluralityof anode pads; two raised and parallel rails formed on the supportingsurface and being integrally formed with the support block, the twoparallel rails encircling the cathode and anode pads and forming agroove that runs between each of the rails; an elastic o-ring that isset within the groove created by the parallel rails; electrical tracesthat connect the cathode and anode pads with respective contact pads; afirst photonic device attached to a respective one of the cathode padsand connected to at least one of the anode pads; a receptacle that isattached to the supporting surface, the receptacle having a protrudingrim that conforms to the outline of the parallel rails and which is setwithin the groove whereby the o-ring is compressed between the two railsand the rim, the receptacle also having a first receptacle opening; anda first glass lens attached within the first receptacle opening suchthat the first glass lens is positioned above the first photonic device,wherein the first photonic device is sealed between the receptacle, thefirst glass lens, and the supporting surface.
 18. An opticaltransmission device as recited in claim 17 wherein the receptaclefurther comprises: at least one stem that is in contact with the supportsurface, the stem acting to maintain a standoff separation distancebetween the first glass lens and the first photonic device.
 19. Anoptical transmission device as recited in claim 17 further comprising:at least one interconnecting wire that extends outwardly from a topsurface of the first photonic device and then bends back to make contactwith one of the anode pads, whereby the interconnecting wire serves toconnect the first photonic device to the anode pad; and wherein the stemmaintains a standoff separation distance sufficient to prevent theinterconnecting wire from making contact with the first glass lens. 20.An optical transmission device recited in claim 17 wherein the supportblock is formed of multiple laminated layers of ceramic material, andwherein the electrical traces are formed by a plurality of conductivepathways that are sandwiched between adjacent ceramic layers andconductive vias that pass through the thickness of each of the ceramiclayers in order to connect the conductive pathways.
 21. An opticaltransmission device recited in claim 17 further comprising: a secondphotonic device attached to a respective one of the cathode pads andconnected to at least one of the anode pads; and wherein the receptaclehas a second receptacle opening that includes a second glass lens thatis positioned above the second photonic device.
 22. An opticaltransmission device recited in claim 21 wherein both of the first andsecond photonic devices are either light transmitting or receivingdevices.
 23. An optical transmission device recited in claim 21 whereinthe first photonic device is a light transmitting device and the secondphotonic device is a light receiving device, and wherein the first glasslens is configured to attenuate the light transmitted from the firstphotonic device.
 24. An optical transmission device recited in claim 17further comprising: a packaged semiconductor device package thatincludes a semiconductor die that is packaged within a protectivemolding material, a first set of electrical contact surfaces that areattached to the contact pads on the mounting surface of the supportblock, and a second set of contact surfaces capable of being connectedto an external system.
 25. An optical transmission device comprising: asupport block having a supporting surface and a mounting surface, themounting surface having a plurality of contact pads, and the supportingsurface having at least one cathode pad and a plurality of anode pads;electrical traces that connect the cathode and anode pads withrespective contact pads; a first photonic device attached to arespective one of the cathode pads and connected to at least one of theanode pads; a receptacle that is attached to the supporting surface, thereceptacle securing a first glass lens such that is it positioned abovethe first photonic device, the receptacle also having a protruding rimthat is in contact with the supporting surface, the receptacle having areceptacle cavity that fits over the photonic device whereby thephotonic device is sealed between the supporting surface and thereceptacle; and adhesive material applied to the contact area betweenthe protruding rim and the supporting surface.
 26. An opticaltransmission device as recited in claim 25 further comprising: a secondphotonic device attached to a respective one of the cathode pads andconnected to at least one of the anode pads; and a second glass lenssecured by the receptacle such that the second glass lens is positionedabove the second photonic device.
 27. An optical transmission devicerecited in claim 26 wherein both of the first and second photonicdevices are either light transmitting or receiving devices.
 28. Anoptical transmission device recited in claim 26 wherein the firstphotonic device is a light transmitting device and the second photonicdevice is a light receiving device, and wherein the first glass lens isconfigured to attenuate the light transmitted from the first photonicdevice.
 29. An optical transmission device recited in claim 25 furthercomprising: a packaged semiconductor device package that includes asemiconductor die that is packaged within a protective molding material,a first set of electrical contact surfaces that are attached to thecontact pads on the mounting surface of the support block, and a secondset of contact surfaces capable of being connected to an externalsystem.
 30. An optical transmission device comprising: an impermeablesupport block having a supporting surface and a mounting surface, themounting surface having a plurality of contact pads, and the supportingsurface having at least one cathode pad and a plurality of anode pads; agroove formed within the supporting surface, the groove encircling thecathode and anode pads; an elastic oaring that is set within the groove;electrical traces that connect the cathode and anode pads withrespective contact pads; a first photonic device attached to arespective one of the cathode pads and connected to at least one of theanode pads; a receptacle that is attached to the supporting surface, thereceptacle having a protruding rim that conforms to the outline of thegroove, the rim being inserted into the groove whereby the o-ring iscompressed, the receptacle also having a first receptacle opening; and afirst glass lens attached within the first receptacle opening such thatthe first glass lens is positioned above the first photonic device,wherein the first photonic device is sealed between the receptacle, thefirst glass lens, and the supporting surface.
 31. An opticaltransmission device as recited in claim 30 wherein the receptaclefurther comprises: at least one stem that is in contact with the supportsurface, the stem acting to maintain a standoff separation distancebetween the first glass lens and the first photonic device.
 32. Anoptical transmission device as recited in claim 30 further comprising:at least one interconnecting wire that extends outwardly from a topsurface of the first photonic device and then bends back to make contactwith one of the anode pads, whereby the interconnecting wire serves toconnect the first photonic device to the anode pad; and wherein the stemmaintains a standoff separation distance sufficient to prevent theinterconnecting wire from making contact with the first glass lens.